A graph is a data expression form advantageous for describing inter-pixel relation information, and a graph-based signal processing scheme of processing inter-pixel relation information by expressing it as a graph has been utilized. In the graph-based signal processing, concepts such as sampling, filtering, conversion, and the like, may be generalized using a graph in which each signal sample indicates a vertex and relations of signals are indicated as graph edges having a positive weight.
In such graph-based signal processing, residual signals may have quite different statistical characteristics depending on prediction methods. Accordingly, it is necessary to improve compression efficiency using an optimum transform kernel into which a characteristic according to a prediction method has been incorporated.